Path generation apparatus

ABSTRACT

Path generation apparatus, includes: sensor mounted on vehicle and detecting external situation with advancing direction of vehicle as center; and ECU including processor and memory. ECU perform: acquiring location information of object in surrounding area of vehicle based on external situation detected by sensor; generating target path of vehicle based on location information; determining whether buffer area within predetermined range in width direction from vehicle-traveling-in-parallel in adjacent lane overlaps target path based on location information; offsetting target path in direction away from vehicle-traveling-in-parallel when buffer area overlaps target path; determining whether vehicle-traveling-in-parallel in left adjacent lane and vehicle-traveling-in-parallel in right adjacent lane are present within predetermined range based on location information; and prohibiting offsetting of target path when vehicle-traveling-in-parallel in left adjacent lane and vehicle-traveling-in-parallel in right adjacent lane are present within the predetermined range.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2022-114687 filed on Jul. 19, 2022, thecontent of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to a path generation apparatus configured togenerate a target traveling path of a vehicle having an automaticdriving function or a driving assistance function.

Description of the Related Art

There has been conventionally known a device that generates a targetpath of a vehicle having a driving assistance function (for example, seeJP 2015-058920 A). In the device described in JP 2015-058920 A,traveling paths of a preceding vehicle and an entering vehicle areacquired, and a target traveling path of the self-vehicle is set, basedon the traveling path of the entering vehicle, when and after a locationpoint where a deviation amount of the traveling paths of the precedingvehicle and the entering vehicle is equal to or smaller than apredetermined value.

As vehicles each having an automatic driving function and/or a drivingassistance function become widely used, safety and convenience of theentire transportation society are improved, and sustainabletransportation systems are achievable. In addition, since the efficiencyand smoothness of transportation are improved, the CO₂ emission amountis reduced, and the load on environment can be reduced.

In a case where the vehicle width of a vehicle traveling in parallel inan adjacent lane is large, by the way, a target path is desirablygenerated to keep a certain distance from the vehicle traveling inparallel in order to reduce an uneasy feeling of an occupant. However,in a case where such vehicles traveling in parallel are present on bothleft and right sides, and when a traveling scene in which theself-vehicle overtakes the vehicle traveling in parallel or theself-vehicle is overtaken by the vehicle traveling in parallelcontinues, the target path is frequently changed, and this may give theoccupant a sense of incongruity conversely.

SUMMARY OF THE INVENTION

An aspect of the present invention is a path generation apparatus,including: an external sensor mounted on a self-vehicle and configuredto detect an external situation with an advancing direction of theself-vehicle as a center; and an electronic control unit including aprocessor and a memory coupled to the processor. The electronic controlunit is configured to perform: acquiring location information of anobject in a surrounding area of the self-vehicle based on the externalsituation detected by the external sensor; generating a target path ofthe self-vehicle based on the location information; determining whethera buffer area within a predetermined range in a vehicle width directionfrom a vehicle traveling in parallel in an adjacent lane adjacent to anown lane in which the self-vehicle is traveling overlaps the target pathbased on the location information; offsetting the target path in adirection away from the vehicle traveling in parallel when it isdetermined that the buffer area overlaps the target path; determiningwhether the vehicle traveling in parallel in a left adjacent laneadjacent to a left side of the own lane and the vehicle traveling inparallel in a right adjacent lane adjacent to a right side of the ownlane are present within the predetermined range based on the locationinformation; and prohibiting the offsetting of the target path when itis determined that the vehicle traveling in parallel in the leftadjacent lane and the vehicle traveling in parallel in the rightadjacent lane are present within the predetermined range.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, and advantages of the present invention willbecome clearer from the following description of embodiments in relationto the attached drawings, in which:

FIG. 1 is a block diagram schematically illustrating an example of aconfiguration of main components of a path generation apparatusaccording to an embodiment of the present invention;

FIG. 2 is a diagram for describing generation of a reference target pathby a path generation unit in FIG. 1 ;

FIG. 3 is a diagram for describing determination of whether it isnecessary to offset the reference target path by a first determinationunit in FIG. 1 ;

FIG. 4 is a diagram for describing target path in a traveling scene inwhich neither buffer areas of vehicles traveling in parallel on the leftand right sides overlaps the reference target path;

FIG. 5A is a diagram for describing the target path in a traveling scenein which the buffer area of the vehicle traveling in parallel on theleft side overlaps the reference target path, when not prohibitingoffset;

FIG. 5B is a diagram for describing the target path in a traveling scenein which the buffer area of the vehicle traveling in parallel on theleft side overlaps the reference target path, when prohibiting offset;

FIG. 6A is a diagram for describing the target path in a traveling scenein which the buffer area of the vehicle traveling in parallel on theright side overlaps the reference target path, when not prohibitingoffset;

FIG. 6B is a diagram for describing the target path in a traveling scenein which the buffer area of the vehicle traveling in parallel on theright side overlaps the reference target path, when prohibiting offset;

FIG. 7A is a diagram for describing the target path in a traveling scenein which the buffer areas of the vehicles traveling in parallel on theleft and right sides overlap the reference target path, when notprohibiting offset;

FIG. 7B is a diagram for describing the target path in a traveling scenein which the buffer areas of the vehicles traveling in parallel on theleft and right sides overlap the reference target path, when prohibitingoffset; and

FIG. 8 is a flowchart illustrating an example of path generationprocessing performed by an ECU in FIG. 1 .

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to FIGS. 1 to 8 . A path generation apparatus according to anembodiment of the present invention is applied to a vehicle having adriving assistance function of performing driving assistance for adriver of a self-vehicle or controlling a traveling actuator toautomatically drive the self-vehicle, and generates a target path(target traveling path) of the self-vehicle. The “driving assistance” inthe present embodiment includes driving assistance for assisting adriver's driving operation and automatic driving for automaticallydriving the vehicle regardless of the driver's driving operation, andcorresponds to automatic driving of levels 1 to 4 defined by SAE, andthe “automatic driving” corresponds to automatic driving of level 5.

During the driving assistance or the automatic driving, for example, atarget path is generated along the center of its own lane, based on arecognition result of the surroundings of the self-vehicle by a cameraor the like, and a steering mechanism of the self-vehicle is controlledto travel along the generated target path. In addition, for example, adriving mechanism and a braking mechanism are controlled so that theself-vehicle travels keeping a certain distance from a precedingvehicle. In this case, when a vehicle traveling in parallel changeslanes (cuts in) from an adjacent lane to the own lane and becomes apreceding vehicle, the driving mechanism and the braking mechanism arecontrolled so that the self-vehicle travels keeping a certain distancefrom such a preceding vehicle.

Nevertheless, when the steering mechanism is controlled to simply travelalong the target path along the center of the own lane, in a case wherethe vehicle width of the vehicle traveling in parallel is large or whilethe vehicle traveling in parallel is traveling closer to the own lane,the occupant may feel uneasy. Therefore, in the present embodiment, thepath generation apparatus is configured to offset the target path in adirection away from the vehicle traveling in parallel near the own laneso as to keep a certain distance from not only the preceding vehicle butalso the vehicle traveling in parallel.

In this situation, in a case where vehicles traveling in parallel nearthe own lane are present on both left and right sides, and when thetraveling scene in which the self-vehicle overtakes the vehicletraveling in parallel or the self-vehicle is overtaken by the vehicletraveling in parallel continues, the target path is frequently changed,and this may give the occupant a sense of incongruity conversely.Accordingly, in the present embodiment, the path generation apparatus isconfigured as follows to prohibit offset of the target path depending onthe traveling scene, so that frequent changes in the target path can besuppressed.

FIG. 1 is a block diagram schematically illustrating an example of aconfiguration of main components of a path generation apparatus(hereinafter, a device) 100 according to an embodiment of the presentinvention. As illustrated in FIG. 1 , the apparatus 100 mainly includesan electronic control unit (ECU) 10. The ECU 10 includes a computerincluding a CPU, a RAM, a ROM, an I/O interface, and other peripheralcircuits. The ECU 10 is configured, for example, as a part of aplurality of ECU groups that are mounted on a self-vehicle 1 and thatcontrol the movement of the self-vehicle 1.

A traveling actuator 2 mounted on the self-vehicle 1 and an externalsensor 3 are connected with the ECU 10. The traveling actuator 2includes a driving mechanism such as an engine or a motor that drivesthe self-vehicle 1, a braking mechanism such as a brake that applies thebrakes on the self-vehicle 1, and a steering mechanism such as asteering gear that steers the self-vehicle 1.

The external sensor 3 detects an external situation including a locationof an object in a surrounding area of the self-vehicle 1. The externalsensor 3 includes an imaging element such as a CCD or a CMOS, andincludes a camera that images the surroundings of the self-vehicle 1.The external sensor 3 may include a distance detection unit that detectsa distance from the self-vehicle 1 to an object in a surrounding area.The distance detection unit includes, for example, a millimeter waveradar that emits a millimeter wave (radio wave) and measures a distanceand a direction to an object from a time until the emitted wave hits theobject and returns. The distance detection unit may include a LiDAR thatemits laser light and measures a distance and a direction to an objectfrom a time until the irradiated light hits the object and returns.

The ECU 10 includes, as a functional configuration of the CPU, asurroundings recognition unit 11, a path generation unit 12, a firstdetermination unit 13, an offset unit 14, a second determination unit15, an offset prohibition unit 16, and a travel control unit 17. Thatis, the CPU of the ECU 10 functions as the surroundings recognition unit11, the path generation unit 12, the first determination unit 13, theoffset unit 14, the second determination unit 15, the offset prohibitionunit 16, and the travel control unit 17.

The surroundings recognition unit 11 recognizes locations of a divisionline, a curbstone, a guardrail, and the like on a road in surroundingareas with an advancing direction of the self-vehicle 1 as the center,based on signals from the external sensor 3, and thus recognizes an ownlane LO in which the self-vehicle 1 is traveling. In addition, adjacentlanes LA and LB (a left adjacent lane LA and a right adjacent lane LB)adjacent to the left and right sides of the own lane LO are recognized.

The surroundings recognition unit 11 further recognizes other vehiclesby recognizing the locations of contours of other vehicles including apreceding vehicle traveling on a forward side of the self-vehicle 1 inthe own lane LO, a following vehicle traveling on a rearward side of theself-vehicle 1, and the vehicles 4A and 4B traveling in parallelrespectively in the adjacent lanes LA and LB. The vehicles 4A and 4Btraveling in parallel include vehicles 4A and 4B traveling in parallelrespectively in the adjacent lanes LA and LB on a forward side of theself-vehicle 1 and vehicles 4A and 4B traveling in parallel respectivelyin the adjacent lanes LA and LB on a rearward side of the self-vehicle1.

That is, the surroundings recognition unit 11 acquires locationinformation of objects in surrounding areas of the self-vehicle 1including the traveling lane and other vehicles, based on the signalsfrom the external sensor 3. In other words, the external sensor 3 andthe surroundings recognition unit 11 function as an informationacquisition unit that acquires the location information of objects insurrounding areas of the self-vehicle 1.

FIG. 2 is a diagram for describing generation of a reference target pathR1 by the path generation unit 12. The path generation unit 12 generatesthe reference target path R1, for example, along the center of the ownlane LO in which the self-vehicle 1 is traveling, based on a recognitionresult of the surroundings recognition unit 11. A general road shape isdesigned by use of a clothoid curve in which a curvature changes at aconstant rate, and some sections of the clothoid curve corresponding tothe road shape can be approximated by use of a high-order function suchas a cubic function. They may be approximated by use of a vehiclemovement model such as a two-wheeled model.

The path generation unit 12 identifies an advancing direction of theself-vehicle 1 with respect to the own lane LO, based on the recognitionresult of the surroundings recognition unit 11, and derives a cubicfunction F(X) representing the center line of the own lane LO with thecurrent location point of the self-vehicle 1 as the origin O and theidentified advancing direction as X axis. That is, the cubic functionsF_(L)(X) and F_(R) (X) of following expressions (i) and (ii), whichapproximate the left and right division lines (or curbstones, guardrails, or the like) that have been recognized by the surroundingsrecognition unit 11, are derived in a curve fitting method such as aleast squares method.

F _(L)(X)=C _(3L) X ³ +C _(2L) X ² +C _(1L) X+C _(0L)  (i)

F _(R)(X)=C _(3R) X ³ +C _(2R) X ² +C _(1R) X+C _(0R)  (ii)

Next, a cubic function F(X) of the following formula (iii) correspondingto the center line of the own lane LO is derived, based on the cubicfunctions F_(L)(X) and F_(R) (X) respectively corresponding to the leftand right division lines, and a normal reference target path R1 isgenerated along the center line represented by the cubic function F(X)that has been derived.

F(X)=C ₃ X ³ +C ₂ X ² +C ₁ X+C ₀  (iii)

C ₃=(C _(3L) +C _(3R))/2,C ₂=(C _(2L) +C _(2R))/2,

C ₁=(C _(1L) +C _(1R))/2,C ₀=(C _(0L) +C _(0R))/2

FIG. 3 is a diagram for describing determination of whether it isnecessary to offset the reference target path R1 by the firstdetermination unit 13. As illustrated in FIG. 3 , the firstdetermination unit 13 determines whether a buffer area 5 within apredetermined range in the vehicle width direction from the vehicles 4Aand 4B traveling in parallel overlaps the reference target path R1,based on the recognition results of the surroundings recognition unit11. In other words, whether a following expression (iv) is establishedis determined. In the following expression (iv), “YA” represents a Ycoordinate of a right end of the vehicle 4A traveling in parallel on aleft side, “YB” represents a Y coordinate of a left end of the vehicle4B traveling in parallel on a right side that have been recognized bythe surroundings recognition unit 11, and “W” represents a length of thepredetermined range in the vehicle width direction.

YB+W≤F(X)≤YA−W  (iv)

In a case of determining that the buffer area 5 overlaps the referencetarget path R1 (the expression (iv) is not established), the firstdetermination unit 13 determines that it is necessary to offset thereference target path R1 in order to reduce the uneasy feeling of theoccupant. The width of the buffer area 5 to be used when the firstdetermination unit 13 determines whether it is necessary to offset thereference target path R1, that is, the length W of the predeterminedrange in the vehicle width direction is predefined to a predeterminedvalue (for example, approximately 2.0 m to 2.4 m), based on a testresult by a skilled driver.

FIGS. 4 to 7B are diagrams for describing final target paths in varioustraveling scenes. As illustrated in FIG. 4 , in a traveling scene inwhich neither the buffer area 5 of the vehicle 4A traveling in parallelon the left side nor the buffer area 5 of the vehicle 4B traveling inparallel on the right side overlaps the reference target path R1, thereference target path R1 that has been generated by the path generationunit 12 is determined as the final target path without change.

On the other hand, as illustrated in FIG. 5A, in a traveling scene inwhich the buffer area 5 of the vehicle 4A traveling in parallel on theleft side overlaps the reference target path R1, the first determinationunit 13 determines that it is necessary to offset the reference targetpath R1. In this case, the offset unit 14 first determines whether atleast one of the vehicles 4A and 4B traveling in parallel has movedacross the division line and has cut in the own lane LO, permits theoffset in a case of determining that the vehicle has not cut in, andprohibits the offset in a case of determining that the vehicle has cutin. In a case where it is determined that at least one of the vehicles4A and 4B traveling in parallel has cut in and the offset of thereference target path R1 by the offset unit 14 is prohibited, thereference target path R1 that has been generated by the path generationunit 12 is determined as the final target path.

In a case where it is determined that neither the vehicle 4A travelingin parallel nor the vehicle 4B traveling in parallel has moved acrossthe division line or has cut in the own lane LO, the offset of thereference target path R1 by the offset unit 14 is permitted. In thissituation, in a case where the first determination unit 13 determinesthat the buffer area 5 of the vehicle 4A traveling in parallel on theleft side overlaps the reference target path R1, the offset unit 14offsets the reference target path R1 in a direction away from thevehicle 4A traveling in parallel on the left side. More specifically,the reference target path R1 is offset to avoid the buffer area 5 of thevehicle 4A traveling in parallel on the left side, and an offset path R2is generated.

The second determination unit 15 determines whether the vehicle 4Atraveling in parallel on the left side and the vehicle 4B traveling inparallel on the right side are present within a predetermined range inthe advancing direction of the self-vehicle 1, based on the recognitionresults by the surroundings recognition unit 11 (an offset prohibitiondetermination of the reference target path R1). In a case where it isdetermined that the vehicle 4A traveling in parallel on the left sideand the vehicle 4B traveling in parallel on the right side are presentwithin the predetermined range in the advancing direction, the seconddetermination unit 15 determines that the current traveling scene is atraveling scene that may give the occupant a sense of incongruityconversely caused by offsetting the reference target path R1.

A length D of the predetermined range in the advancing direction to beused when the second determination unit 15 makes the offset prohibitiondetermination of the reference target path R1 is defined with theself-vehicle 1 as a reference. The length from the self-vehicle 1 to afront end of the predetermined range in the advancing direction and thelength from the self-vehicle 1 to a rear end of the predetermined rangein the advancing direction may be defined to the same length or may bedefined to different lengths. The length D of the predetermined range inthe advancing direction may be corrected in accordance with a travelingspeed of the self-vehicle 1, traveling speeds of the vehicles 4A and 4Btraveling in parallel, or a traveling speed of the following vehicle, ormay be corrected in accordance with the type of a road on which theself-vehicle 1 is traveling, a weather condition, or the like.

In a case where the second determination unit 15 determines that neitherthe vehicle 4A traveling in parallel on the left side nor the vehicle 4Btraveling in parallel on the right side is present within thepredetermined range in the advancing direction, the offset path R2 thathas been generated by the offset unit 14 is determined as the finaltarget path.

On the other hand, in a case where the second determination unit 15determines that the vehicle 4A traveling in parallel on the left sideand the vehicle 4B traveling in parallel on the right side are presentwithin the predetermined range in the advancing direction, the offsetprohibition unit 16 prohibits the offset unit 14 from offsetting thereference target path R1, as illustrated in FIG. 5B. More specifically,a cross-border amount ca (FIG. 5A), by which the buffer area 5 (a rightend of the buffer area 5) of the vehicle 4A traveling in parallel on theleft side has moved across the reference target path R1 in the vehiclewidth direction, is calculated, and a setback of narrowing the bufferarea of the vehicle 4A traveling in parallel on the left side by thecross-border amount ca that has been calculated is performed.

In an example of FIG. 5B, the buffer area 5 of the vehicle 4A travelingin parallel on the left side is subject to the setback. In thissituation, a following expression (v) is established and the firstdetermination unit 13 determines that the buffer area 5 of the vehicle4A traveling in parallel on the left side does not overlap the referencetarget path R1. Therefore, it is determined that it is not necessary tooffset the reference target path R1, and thus the offset of thereference target path R1 is prohibited. In this case, the referencetarget path R1 that has been generated by the path generation unit 12 isdetermined as the final target path.

YB+W≤F(X)≤YA−W+εa  (v)

As illustrated in FIG. 6A, also in a travel scene in which the bufferarea 5 of the vehicle 4B traveling in parallel on the left side overlapsthe reference target path R1 (does not cut in), the first determinationunit 13 determines that it is necessary to offset the reference targetpath R1, and the offset unit 14 generates the offset path R2. Then, in acase where the second determination unit 15 determines that the vehicle4A traveling in parallel on the left side and the vehicle 4B travelingin parallel on the right side are present within the predetermined rangein the advancing direction, the offset prohibition unit 16 calculatesthe cross-border amount εb (FIG. 6A), and the buffer area 5 of thevehicle 4B traveling in parallel on the right side is subject to thesetback, as illustrated in FIG. 6B. In this case, a following expression(vi) is established, and the first determination unit 13 determines thatthe buffer area 5 of the vehicle 4B traveling in parallel on the rightside does not overlap the reference target path R1. Therefore, it isdetermined that it is not necessary to offset the reference target pathR1, and thus the offset of the reference target path R1 is prohibited.Also in this case, the reference target path R1 that has been generatedby the path generation unit 12 is determined as the final target path.

YB+W−εb≤F(X)≤YA−W  (vi)

As illustrated in FIG. 7A, also in a travel scene in which the bufferareas 5 of the vehicles 4A and 4B traveling in parallel on both the leftand right sides overlap the reference target path R1 (do not cut in),the first determination unit 13 determines that it is necessary tooffset the reference target path R1, and the offset unit 14 generatesthe offset path R2. Then, in a case where the second determination unit15 determines that the vehicle 4A traveling in parallel on the left sideand the vehicle 4B traveling in parallel on the right side are presentwithin the predetermined range in the advancing direction, the offsetprohibition unit 16 calculates the cross-border amounts εa and εb (FIG.7A), and both the left and right buffer areas 5 are subject to thesetback, as illustrated in FIG. 7B. In this case, a following expression(vi) is established and the first determination unit 13 determines thatneither the buffer area 5 on the left side nor the buffer area 5 on theright side overlaps the reference target path R1. Therefore, it isdetermined that it is not necessary to offset the reference target pathR1, and thus the offset of the reference target path R1 is prohibited.Also in this case, the reference target path R1 that has been generatedby the path generation unit 12 is determined as the final target path.

YB+W−εb≤F(X)≤YA−W+εa  (vii)

The travel control unit 17 controls the traveling actuator 2 so that theself-vehicle 1 travels along the finally determined target path.Accordingly, even though the traveling scene in which the self-vehicle 1overtakes the vehicles 4A and 4B traveling in parallel or theself-vehicle 1 is overtaken by the vehicles 4A and 4B traveling inparallel continues, the frequent changes in the target path aresuppressed, so that smooth vehicle behaviors are achievable. Note thatwhen the vehicles 4A and 4B traveling in parallel cut in the own lane LOand become the preceding vehicles, the driving mechanism and the brakingmechanism are controlled to travel on the center of the own lane LO (onthe reference target path R1) keeping a certain distance from thepreceding vehicles, so that smooth vehicle behaviors are achievable.

FIG. 8 is a flowchart illustrating an example of path generationprocessing performed by the ECU 10. The processing illustrated in thisflowchart starts, for example, when the self-vehicle 1 starts up and theECU 10 is activated, and is repeatedly performed at a predeterminedcycle corresponding to the processing cycle of the ECU 10.

As illustrated in FIG. 8 , in the path generation processing, first, inS1 (S: processing step), the own lane LO is recognized, based on asignal from the external sensor 3, and the reference target path R1 isgenerated, based on a recognition result. Next, in S2, it is determinedwhether at least one of the vehicles 4A and 4B traveling in parallel hasmoved across the division line and has cut in the own lane LO. In a casewhere a negative determination is made in S2, the processing proceeds toS3, and in a case where a positive determination is made, the processingproceeds to S4. In S3, the vehicles 4A and 4B traveling in parallel onthe left and right sides and the buffer areas 5 corresponding to themare respectively recognized, based on the signal from the externalsensor 3, and it is determined whether each buffer area 5 overlaps thereference target path R1 generated in S1, based on the recognitionresult. In a case where a negative determination is made in S3, theprocessing proceeds to S4, and the reference target path R1 generated inS1 is determined as the final target path.

On the other hand, in a case where a positive determination is made inS3, the processing proceeds to S5, the reference target path R1generated in S1 is offset to avoid the buffer area 5, and the offsetpath R2 is generated. Next, in S6, it is determined whether the vehicle4A traveling in parallel on the left side and the vehicle 4B travelingin parallel on the right side are present within the predetermined rangein the advancing direction of the self-vehicle 1. In a case where anegative determination is made in S6, the processing proceeds to S7, andthe offset path R2 generated in S5 is determined as the final targetpath.

On the other hand, in a case where a positive determination is made inS6, the processing proceeds to S8, and the cross-border amounts εa andεb of the buffer areas 5 on the left and right sides are respectivelycalculated. Next, in S9, the buffer areas 5 recognized in S3 arerespectively subject to the setback by the cross-border amounts ca andεb calculated in S8, and the processing returns to S3. In this case, anegative determination is made in S3, and the reference target path R1is determined as the final target path in S4.

In this manner, in the traveling scene in which the buffer areas 5 ofthe vehicles 4A and 4B traveling in parallel overlap the referencetarget path R1, the reference target path R1 is offset in the directionaway from the vehicles 4A and 4B traveling in parallel (S3, S5, S7), sothat the traveling path that can reduce the uneasy feeling of theoccupant can be generated. In addition, the offset of the referencetarget path R1 is prohibited in the traveling scene in which the vehicle4A traveling in parallel on the left side and the vehicle 4B travelingin parallel on the right side are present within the predetermined rangein the advancing direction (S6 to S9, S3 to S4), so that it is possibleto prevent the occupant from feeling a sense of incongruity converselycaused by the offset.

Further, the offset is prohibited by the setback of the buffer area 5 bythe cross-border amount ε, which is an amount that the buffer area 5 hasmoved across the reference target path R1 in the vehicle width direction(S8 to S9), so that the offset of the reference target path R1 can beprohibited smoothly. That is, while maintaining the basic processingpattern (S1 to S5) for determining whether to offset the referencetarget path R1, based on the determination result as to whether thebuffer area 5 overlaps the reference target path R1, the offset of thereference target path R1 can be prohibited smoothly.

According to the present embodiment, the following operations andeffects are achievable.

(1) The apparatus 100 includes: the external sensor 3 and thesurroundings recognition unit 11 that acquire location information of anobject in a surrounding area of the self-vehicle 1; the path generationunit 12 that generates the reference target path R1 of the self-vehicle1, based on the location information that has been acquired by theexternal sensor 3 and the surroundings recognition unit 11; the firstdetermination unit 13 that determines whether the buffer area 5 within apredetermined range in the vehicle width direction from the vehicles 4Aand 4B respectively traveling in parallel in the adjacent lanes LA andLB adjacent to the own lane LO in which the self-vehicle 1 is travelingoverlaps the reference target path R1 that has been generated by thepath generation unit 12, based on the location information that has beenacquired by the external sensor 3 and the surroundings recognition unit11; the offset unit 14 that offsets the reference target path R1 in adirection away from the vehicles 4A and 4B traveling in parallel, in acase where the first determination unit 13 determines that the bufferarea 5 (at least one buffer area 5) overlaps the target path; the seconddetermination unit 15 that determines whether the vehicle 4A travelingin parallel on the left side in the left adjacent lane LA adjacent tothe left side of the own lane LO and the vehicle 4B traveling inparallel on the right side in the right adjacent lane LB adjacent to theright side of the own lane LO are present within the predetermined rangein the advancing direction of the self-vehicle 1, based on the locationinformation that has been acquired by the external sensor 3 and thesurroundings recognition unit 11; and the offset prohibition unit 16that prohibits the offset unit 14 from offsetting the reference targetpath R1, in a case where the second determination unit 15 determinesthat the vehicle 4A traveling in parallel on the left side and thevehicle 4B traveling in parallel on the right side are present withinthe predetermined range in the advancing direction (FIG. 1 ).

In a case where the vehicles 4A and 4B traveling in parallel arerespectively present in the left and right adjacent lanes LA and LB, thetraveling scene in which the self-vehicle 1 overtakes any of thevehicles 4A and 4B traveling in parallel or the self-vehicle 1 isovertaken by any of the vehicles 4A and 4B traveling in parallelcontinues in some cases. In such cases, if the reference target path R1is offset whenever the vehicle 4A or 4B traveling in parallel having alarge vehicle width or the vehicle 4A or 4B traveling in parallel to becloser to the own lane LO appears on a forward side of the self-vehicle1, the target path will be frequently changed, and this may give theoccupant a sense of incongruity conversely.

In a case where the vehicles 4A and 4B traveling in parallel on both theleft and right sides are present, the offset of the reference targetpath R1 is prohibited. Thus, even though the traveling scene in whichthe self-vehicle overtakes the vehicle traveling in parallel or theself-vehicle is overtaken by the vehicle traveling in parallelcontinues, the frequent changes in the target path are suppressed, sothat smooth vehicle behaviors are achievable. In addition, in a casewhere the vehicle 4A or 4B traveling in parallel cuts in the own lane LOand becomes a preceding vehicle, the driving mechanism and the brakingmechanism are controlled to travel on the center of the own lane LO (onthe reference target path R1) keeping a certain distance from thepreceding vehicle, so that smooth vehicle behaviors are achievable.

(2) In a case where the second determination unit 15 determines that thevehicle 4A traveling in parallel and the vehicle 4B traveling inparallel are present within the predetermined range in the advancingdirection, and in a case where the first determination unit 13determines that any of the buffer area 5 corresponding to the vehicle 4Atraveling in parallel on the left side and the buffer area 5corresponding to the vehicle 4B traveling in parallel on the right sideoverlaps the reference target path R1, the offset prohibition unit 16prohibits the offset unit 14 from offsetting the reference target pathR1 (FIGS. 5B and 6B).

(3) In a case where the second determination unit 15 determines that thevehicle 4A traveling in parallel on the left side and the vehicle 4Btraveling in parallel on the right side are present within thepredetermined range in the advancing direction, and in a case where thefirst determination unit 13 determines that both the buffer area 5corresponding to the vehicle 4A traveling in parallel on the left sideand the buffer area 5 corresponding to the vehicle 4B traveling inparallel on the right side overlap the reference target path R1, theoffset prohibition unit 16 prohibits the offset unit 14 from offsettingthe reference target path R1 (FIG. 7B).

(4) The offset prohibition unit 16 calculates the cross-border amount cby which the buffer area 5 has moved across the reference target path R1in the vehicle width direction, based on the location information thathas been acquired by the external sensor 3 and the surroundingsrecognition unit 11, and narrows the buffer area 5 by the cross-borderamount c that has been calculated to prohibit the offset unit 14 fromoffsetting the reference target path R1 (FIGS. 5B, 6B, and 7B). In thiscase, it is possible to smoothly prohibit the offset of the referencetarget path R1 while maintaining the basic processing pattern fordetermining whether to offset the reference target path R1, based on thedetermination result as to whether the buffer area 5 overlaps thereference target path R1.

(5) The length W of the predetermined range in the vehicle widthdirection is predefined. For example, it is predefined, based on a testresult by a skilled driver. Accordingly, the reference target path R1can be offset in an appropriate traveling scene in accordance with thedistances to the vehicles 4A and 4B traveling in parallel.

(6) The length D of the predetermined range in the advancing directionis defined with the self-vehicle 1 as a reference. For example, it isdefined with the self-vehicle 1 as a reference, in accordance with thetraveling speed of the self-vehicle 1, the traveling speeds of thevehicles 4A and 4B traveling in parallel, the traveling speed of thefollowing vehicle, the type of a road on which the self-vehicle 1 istraveling, a weather condition, or the like.

(7) The vehicles 4A and 4B traveling in parallel include the vehicles 4Aand 4B traveling in parallel in the adjacent lanes LA and LB on aforward side of the self-vehicle 1 and the vehicles 4A and 4B travelingin parallel in the adjacent lanes LA and LB on a rearward side of theself-vehicle 1.

In the above embodiments, the description has been given with regard toan example in which the surroundings recognition unit 11 acquires thelocation information of an object including the traveling lane and othervehicles in the surrounding areas of the self-vehicle 1, based on thesignal from the external sensor 3. However, the information acquisitionunit that acquires the location information of the object in thesurrounding area of the self-vehicle is not limited to such an example.For example, the location information of the object in the surroundingarea of the self-vehicle may be acquired via vehicle-to-everything (V2X)communication with another vehicle, an infrastructure facility, a cloudserver, or the like.

In the above embodiments, the description has been given with regard toan example in which the path generation unit 12 generates the referencetarget path R1 along the center line of the own lane LO. However, thepath generation unit that generates the target path of the self-vehicleis not limited to such an example. For example, the reference targetpath R1 closer to the outside of the road than to the center line may begenerated, based on a setting value that is changeable in accordancewith a preference of the driver or a learning value based on a travelhistory of the driver. The reference target path R1 closer to the insidein a turning direction than to the center line may be generated inaccordance with a curvature radius of the own lane LO.

In the above embodiments, the description has been given with regard toan example in which the offset prohibition unit 16 performs the setbackof the buffer area 5, and thus prohibits the offset. However, any offsetprohibition unit may be applicable, as long as it prohibits the offsetin a case where it is determined that the vehicles 4A and 4B travelingin parallel on both the left and right sides are present. For example,in the case where it is determined that the vehicles 4A and 4B travelingin parallel on both the left and right sides are present, the offset maybe prohibited by determining the reference target path R1 before theoffset as the final target path (in a case where a positivedetermination is made in S6 of FIG. 8 , the processing proceeds to S4).

In the above embodiments, the description has been given with regard toan example in which the apparatus 100 includes the travel control unit17. However, the path generation apparatus is not limited to such anexample. For example, a display control unit that controls a displayunit such as a head-up display to display a finally determined targetpath superimposed on a road on a forward side of the vehicle may beincluded.

The above embodiment can be combined as desired with one or more of theaforesaid modifications. The modifications can also be combined with oneanother.

According to the present invention, it becomes possible to suppressfrequent changes in the target path.

Above, while the present invention has been described with reference tothe preferred embodiments thereof, it will be understood, by thoseskilled in the art, that various changes and modifications may be madethereto without departing from the scope of the appended claims.

1. A path generation apparatus, comprising: an external sensor mountedon a self-vehicle and configured to detect an external situation with anadvancing direction of the self-vehicle as a center; and an electroniccontrol unit including a processor and a memory coupled to theprocessor, wherein the electronic control unit is configured to perform:acquiring location information of an object in a surrounding area of theself-vehicle based on the external situation detected by the externalsensor; generating a target path of the self-vehicle based on thelocation information; determining whether a buffer area within apredetermined range in a vehicle width direction from a vehicletraveling in parallel in an adjacent lane adjacent to an own lane inwhich the self-vehicle is traveling overlaps the target path based onthe location information; offsetting the target path in a direction awayfrom the vehicle traveling in parallel when it is determined that thebuffer area overlaps the target path; determining whether the vehicletraveling in parallel in a left adjacent lane adjacent to a left side ofthe own lane and the vehicle traveling in parallel in a right adjacentlane adjacent to a right side of the own lane are present within thepredetermined range based on the location information; and prohibitingthe offsetting of the target path when it is determined that the vehicletraveling in parallel in the left adjacent lane and the vehicletraveling in parallel in the right adjacent lane are present within thepredetermined range.
 2. The path generation apparatus according to claim1, wherein the electronic control unit is configured to perform: theprohibiting the offsetting of the target path when it is determinedthat: the vehicle traveling in parallel in the left adjacent lane andthe vehicle traveling in parallel in the right adjacent lane are presentwithin the predetermined range; and one of the buffer area correspondingto the vehicle traveling in parallel in the left adjacent lane and thebuffer area corresponding to the vehicle traveling in parallel in theright adjacent lane overlaps the target path.
 3. The path generationapparatus according to claim 1, wherein the electronic control unit isconfigured to perform: the prohibiting the offsetting of the target pathwhen it is determined that: the vehicle traveling in parallel in theleft adjacent lane and the vehicle traveling in parallel in the rightadjacent lane are present within the predetermined range; and both ofthe buffer area corresponding to the vehicle traveling in parallel inthe left adjacent lane and the buffer area corresponding to the vehicletraveling in parallel in the right adjacent lane overlap the targetpath.
 4. The path generation apparatus according to claim 1, wherein theelectronic control unit is configured to perform: the prohibiting theoffsetting of the target path by: calculating a cross-border amount bywhich the buffer area has moved across the target path in the vehiclewidth direction based on the location information; and narrowing thebuffer area by the calculated cross-border amount.
 5. The pathgeneration apparatus according to claim 1, wherein a length of thepredetermined range in the vehicle width direction is predefined.
 6. Thepath generation apparatus according to claim 1, wherein a length of thepredetermined range in the advancing direction is defined with theself-vehicle as a reference.
 7. The path generation apparatus accordingto claim 1, wherein the vehicle traveling in parallel includes: thevehicle traveling in parallel in the adjacent lane on a forward side ofthe self-vehicle; and the vehicle traveling in parallel in the adjacentlane on a rearward side of the self-vehicle.
 8. The path generationapparatus according to claim 1, wherein the electronic control unit isconfigured to perform: acquiring the location information of the ownlane and the vehicle traveling in parallel based on the externalsituation detected by the external sensor.